Print version ISSN 0100-4042
GUIMARAES, Wesson; ALVES, Maria Isabel Ribeiro and ANTONIOSI FILHO, Nelson Roberto. Anthocyanins in natural extracts: application in acid-base titration and identification by liquid chromatography/mass spectrometry. Quím. Nova [online]. 2012, vol.35, n.8, pp. 1673-1679. ISSN 0100-4042. http://dx.doi.org/10.1590/S0100-40422012000800030.
Anthocyanins extracted from picao, quaresmeira, petunia, flamboyant, purple ipe, lobeira, pata de vaca, jaboticaba, purple cabbage and jambul were evaluated as natural acid-base indicators. Anthocyanins in extracts were identified using HPLC/MS. Clear, rapid change in color at final-point titration was observed for extracts but only picao showed strong change in pH. Indirect determination of carbonate in limestone using a natural indicator was performed and results compared with phenolphthalein indicator and potentiometer titration. Optimal results were obtained with picao but other extracts showed good accuracy and precision.
Keywords : pH; anthocyanins; HPLC.